Known comb-like gaskets for dismountable flanged joints, fittings, pressure vessels, etc., are as a rule, ring shaped or annular shape and have cross-sections of various shapes. This usually depends on the material used for sealing of the flanged joint. As a rule, the flanges are mutually connected by means of screws, through which a dismountable connection is obtained. The dismountable connection is advantageous for executing repairs, reconstructions, etc.
There are known comb-like gaskets, which are made of soft alloy steel or austenitic steel. Mostly, the comb-like gasket is overlain on both sides with sealing board or foil which comprises expanded graphite, expanded Teflon, Thermiculite, mica, aluminium, nickel, silver, etc. Selection of a particular material used for the sealing plate or sealing foil is affected especially by chemical-physical properties of the media, which flows within the pipeline system or which is present in the sealed pressure vessel.
Gaskets for flanged joints are usually ring shaped and are disposed along contact sealing surfaces of the flanges. The gaskets include concentric grooves having a V shape with an opening angle of 90°, a spacing of 1.5 mm and a depth of 0.75 mm. The sealing foil conforms to the V shaped grooves when compressed between the contact sealing surfaces of the flanges. Through this transformation of the sealing lining, the effectiveness of the seal at the flanged joint is increased. The most efficient seal with the longest operational reliability of the sealed flanged joint is influenced not only by the chemical properties of the medium flowing within the pipeline, but also by its temperature and pressure. The seal is also affected by variations in pressure and/or temperature that result during operation of the pipeline, particularly when the variations in pressure and/or temperature are relatively large. The effectiveness of the seal is also influenced by a compressive force caused by fasteners such as screws or bolts which mutually join and tighten the flanges.
A known comb-like gasket is overlain on both sides of the gasket with a foil of expanded graphite that features very good sealing properties even at high specific pressures and high temperatures. Upon compression of the comb-like gasket between the sealing surfaces of the flanges, the foil conforms into the grooves. During installation it is necessary to compress the comb-like gasket such that a continuous layer of expanded graphite is present between peaks of the grooves of the comb-like gasket and a sealing surface of the flange. If a direct contact occurs between the groove peaks of the comb-like gasket and the sealing surface of the flange, the foil of expanded graphite will be cut through, thereby devaluing the effectiveness of the seal. As a result, a repair is required to replace the seal. Moreover, in such cases there are quite often galls on the sealing surfaces of the flanges which result from the contact between the groove peaks and the sealing surface of the flange. These galls may also necessitate repair to the sealing surfaces of the flanges which increases costs and time required for executing the repair.
The above mentioned issues which result from the direct contact of the comb-like gasket with the sealing surfaces of the flanges is improved by a comb-like gasket including the V shaped grooves having an opening angle of 90° between the individual grooves. Using an adhesive to adhere the sealing foil to the comb-like gasket facilitates sticking of the sealing foil to the comb-like gasket. In addition, by sticking the sealing foil to the comb-like gasket, installation and maintenance of the seal are improved. It is advantageous to use an adhesive having a wide thermal operating range.
In some cases, the flanged joints are applied in pipeline systems that are exposed to considerable mechanical and heat stresses. In these cases, especially at flanged joints of larger diameters, the stresses worsen the effectiveness of the seal, the service life and reliability of the sealing joint and the level of achievable surface parallelism of contact surfaces between the connected flanges. Non-parallelism of the contact connection surfaces of the flanges as well as possible surface deformations and irregularities in those surfaces complicate installation and negatively influence the effectiveness of the seal, especially in a case when an annular comb-like two-sided overlain gasket is used for sealing of the joint.
The objective of the invention is to achieve improvement of the background art and to optimise conditions for production of an operationally reliable seal at the flanged joints, as well as a reduction of the negative impact of non-parallelism and deformations of the sealing surfaces of the flanges being connected. In addition, this invention may be utilized to improve installation and repair activities.